We propose to examine at a molecular level the conformational and motional properties of molecules important in interactions occuring at membrane surfaces. The molecules to be examined vary in complexity from simple ones at the heart of membrane structure and interaction, such as the water molecule, to rather complex ones, such as the glycolipids believed to act as receptors for viral proteins, hormones, toxins, and antibodies. Plant lectins, such as ricin, binding to artificial lipid bilayer systems, will be used to mimic recognition and aggregation steps common to many receptor mediated processes in nature. The methodology to be employed is largely based on nuclear magnetic resonance. The data on structural properties of glycolipids will come primarily from residual quadrupolar splitting of headgroup sites specifically enriched in deuterium. The data on motional properties will come from computer aided analysis of deuterium NMR line shapes and from pulse field gradient NMR experiments applied to a variety of small molecules at membrane interfaces. The exploration and development of NMR methodology are as much a part of the aims of this proposal as the investigation of specific biological systems.